TYPING OF PROSTATE TISSUE BY ULTRASONIC SPECTRUM ANALYSIS

Prostate cancer is the highest-incidence cancer and second-leading can cer killer of men in the U.S. Diagnosis now relies virtually exclusive ly on core-needle biopsy, guided by transrectal ultrasound (TRUS). Bec ause of the limitations of TRUS in detecting suspicious regions, biops y often fails to sample cancer that is present or to determine that ex tracapsular cancer exists, which results in false-negative biopsies or inappropriate prostatectomies. Therefore, we conducted this study to investigate the use of spectrum analysis of radio frequency (RF) echo signals as a possible means of reducing the number of false-negative b iopsies and inappropriate prostatectomies. This method utilizes databa ses of parameters derived from normalized power spectra of RF echo sig nals and histologically proven tissue types to determine ranges of par ameter values associated with tissue types of interest. Typing an unkn own tissue is performed by comparing the parameter values of the unkno wn to the value ranges of specific tissue types In the database, Our r esults provide encouraging preliminary discriminant-function distribut ions that suggest an excellent potential for differentiating cancerous from noncancerous prostate tissue far superior in terms of sensitivit y and specificity than means now used to determine whether biopsy is r equired. In addition, we developed images using color to indicate the most likely tissue type throughout the tissue cross section as determi ned by comparisons with database parameter values. These images showed excellent correlation with histology.